In the Lab: Keeping White Roofs White

A white roof coating that can repel both water and dirt, even in the smoggiest cities, is the latest focus of a U.S.-China building science research partnership underway at several federal facilities.

Lawrence Berkeley National Laboratory is developing a superhydrophobic additive that would allow cool roofs to stay cleaner and last longer. The technology would be ideal for cities with elevated pollution levels, according to a research announcement.

Dow Chemical Company via Berkeley Lab

Scientists from Berkeley Lab, Dow Chemical Company and Oak Ridge National Lab aim to develop a coating that can repel water and resist soiling, making white roofs last longer.

The coating project seeks to demonstrate the feasibility of the coatings in China and the United States, according to the team.

According to Berkeley Lab, white roofs help cool buildings, thus saving energy and bringing down air-conditioning costs. They can also help reduce a city’s temperature by reflecting more sunlight back to space.

However, a white roof in China's notoriously polluted cities is likely to turn sooty after a few months, reducing or negating its effectiveness.

Thus, the project will use an accelerated soiling system developed at Berkeley Lab to predict in just three days how well the coating, with the additive, can maintain its reflectance—a process that would take three years of natural exposure, Berkeley Lab says.

Additional project details were not immediately available.

‘Eager to Experiment’

Since it was launched three years ago, the consortium has made steady progress toward the research and development of a number of low-energy technologies for buildings.

Participants have filed patent applications, launched new products, published about 100 articles, and completed five demonstration projects in China that validate and showcase everything from smart windows to advanced lighting controls, according to Berkeley Lab.

The consortium is unique, according to director Nan Zhou, because it gives government researchers the opportunity to collaborate with private companies in one of the world's fastest-growing markets.

Berkeley Lab

The U.S.–China Clean Energy Research Center Building Energy Efficiency Consortium launched three years ago. Here, U.S. and Chinese officials visit the Chinese Academy of Building Research, one of the program's demonstration sites.

In addition to building-envelope technologies, consortium projects are focusing on renewable energy integration, policy incentives and building operation.

In one project, a dimmable, fully automated lighting system is being integrated in a Chinese office building, according to Berkeley Lab.

Another project—recognizing that human behavior is the largest variable in a building's energy efficiency—will integrate behavior into building design simulation tools, potentially reducing energy use by up to 50 percent in new buildings, Berkeley Lab reports.